The present invention relates generally to a fluid pump having an accumulator assembly comprising an accumulator residing in a cavity of a pump housing with a transverse base, and more particularly to an accumulator piston having a protrusion to limit the area of engagement between the piston and a base of the pump housing cavity.
A low pressure fluid accumulator assembly comprising an accumulator temporarily receives and stores fluid flowing through a fluid flow opening in a base of a pump housing cavity. Accumulators generally include an accumulator housing with a longitudinally extending bore to receive a piston. A biasing means is disposed between a floor of the accumulator housing and the piston to bias the piston longitudinally outwardly from the accumulator housing. The piston selectively engages the base of the pump housing cavity.
A gap is required between the piston and the base of the pump housing cavity in order for pressurized fluid to properly flow into the accumulator assembly. If the area of contact between the piston and the fluid flow is reduced to that portion of the piston immediately adjacent the fluid flow opening, insufficient force will be applied to the outwardly biased piston.
A snap ring has typically been inserted into an upper groove of the accumulator housing to limit the longitudinal travel of the piston, providing the necessary gap between the piston and the base of the pump housing cavity. The high spring rate of the snap ring destroys the tooling used to guide the snap ring or directly damages the accumulator housing. Resulting contamination interferes with proper operation of the accumulator assembly. When used in a system critical application such as an antilock brake, in which proper operation of the accumulator assembly is essential during an antilock braking cycle, such contamination is unacceptable.